body {
  margin: 0px;
}
.box-1,
.box-2,
.box-3,
.box-4,
.box-5 {
  height: 300px;
  width: 100vw;
  display: flex;
}
.box-1 {
  /* 水平左开始 */
  justify-content: flex-start;
  /* 垂直顶部开始 */
  align-items: flex-start;
}
.box-2 {
  /* 水平右开始 */
  justify-content: flex-end;
  /* 垂直底部开始 */
  align-items: flex-end;
}
.box-3 {
  /* 水平居中 */
  justify-content: center;
  /* 垂直居中 */
  align-items: center;
}
.box-4 {
  /* 水平中间间隔一致 */
  justify-content: space-between;
  /* 垂直高度一致 */
  align-items: stretch;
}
.box-5 {
  /* 子元素左右间隔相等 */
  justify-content: space-around;
  /* justify-content: space-evenly; */
}

.box4,
.box5,
.box3,
.box2,
.box1:nth-of-type(2n) {
  background-color: aqua;
}

.box4,
.box5,
.box1,
.box2,
.box3 {
  height: 200px;
  width: 200px;
  border: 1px solid;
}

.box4:nth-of-type(2n) {
  height: 250px;
}
/* =========================================================================== */
#main1,
#main2,
#main3 {
  width: 200px;
  height: 300px;
  border: 1px solid #c3c3c3;
  /* display: flex; */
  display: inline-flex;
}
#main1 div:nth-of-type(2n) {
  flex: 0 1 50px;
}
#main3 {
  align-items: center;

}
#main2 {
  /* flex-wrap: wrap-reverse; */
  flex-wrap: wrap;
}

#main3 div,
#main2 div {
  width: 30px;
  height: 30px;
}

.box-abc {
  border: 1px solid;
  width: 390px;
  height: 400px;
  display: flex;
  justify-content: space-around;
  flex-wrap: wrap;
  align-items: center;
}

.abc {
  width: 100px;
  height: 100px;
  background-color: #c3c3c3;
  border-radius: 12px;
  display: flex;
}


.dd{
  background-color: black;
  height: 20px;
  width: 20px;
  border-radius: 50%;
}

.abc:first-child{
  align-items: center;
  justify-content: center;
}
.abc:nth-child(2){
  justify-content: space-evenly;
  align-items: center;
}

.abc:nth-child(3){
  justify-content: space-evenly;
  align-content: space-between;
}
.abc:nth-child(3) .dd:nth-child(2){
  align-self: center;
}
.abc:nth-child(3) .dd:nth-child(3){
  align-self: flex-end;
}

.abc:nth-child(4){
  justify-content: space-evenly;
  flex-direction: column;
}
.abc:nth-child(4)>.dd-1{
  display: flex;
  /* align-content: center; */
  justify-content: space-around;
}
.abc:nth-child(5){
  justify-content: space-evenly;
  flex-direction: column;
  /* align-content: center; */
}
.abc:nth-child(5)>.dd-1{
  display: flex;
  /* align-content: center; */
  justify-content: space-around;
}
.abc:nth-child(5)>.dd{
  justify-content: center;
  align-content: center;
}
.abc:nth-child(6){
  justify-content: space-around;
  flex-direction: column;
}
.abc:nth-child(6)>.dd-1{
  display: flex;
  justify-content: space-around;
}

#ma {
  width: 250px;
  height: 100px;
  border: 1px solid black;
  display: flex;
  align-items: center		;
}

​ #ma div {
  flex: 1;
}